IE: 703px a‰? 703px?

I’ve got a question about pixel width in IE vs. safari, firefox, mozilla and the rest…

the width of my content is 703px and it works fine everywhere, but somehow any class i add to the the main content doesn’t sit nicely in IE. It comes up about 10% short and to the left.

All i’m trying to do is create a navigation menu, horzontally across the top which has a colored background.

Seems like it oughtta just be width: 703px and it is everywhere but IE.

Is there some simple way to make an adjustment which will only appear in IE?

anyone solve this sort of problem before?